The arrests took place at a hotel in Bangkok on Sunday morning, while the suspects were attending a training session in the hotel’s ballroom.

Among those arrested were 60 Thais and 78 foreigners from China, Malaysia, Cambodia, Laos and Myanmar. Most of the foreigners had entered Thailand on tourist visas.

“We have received complaints that training for illegal tour guides was being conducted,” Patrol and Special Operation Division chief Pol Maj-General Surachet Hakphan said on Sunday.

His division and police, including the Tourist Police Division, led dozens of officers in the raid at the hotel.

Participants at the training session, which started on Saturday, told police that they had paid Bt2,000 each to attend the event and had their cell phones taken away during their participation.

“We found that they were being briefed about how to sell products such as facial cleansers, rubber pillows and skincare cream,” Surachai said.

Police are now investigating whether the training was held to teach participants, including foreigners, about how to serve as tour guides and coerce tourists into buying products.

Thai laws bar foreigners from working as tour guides.

Sirikorn Tanachaipornsakul, who organised the training, denied arranging a training session teaching tour-guide services, adding that the event was just a post-Songkran party. However, she admitted promoting some products at the event in the hope of selling them to tourists.

Police said foreigners who had overstayed their visas would face immediate action while those who still had the right to stay would be barred from leaving the country until the investigation is complete.